The present invention relates to an elevator group control apparatus for controlling a group of elevators provided side by side in an building.
In the conventional elevator group control apparatus, for example as disclosed in U.S. Pat. No. 4,244,450, when a floor call is registered, a suitable one of the available elevator cars or cages is assigned to the floor call so that the call can be responded to rapidly. The cages are assigned such that the passengers' average waiting time is minimized and so as not to produce an extreme difference in waiting times for users on different floors.
FIG. 1 shows a conventional elevator group control apparatus for two elevators A and B. In the drawing, 1A designates a hoist of elevator A provided in a machinery room 2; 1B, a similar hoist of elevator B; 3A, a cage of elevator A connected to one end of a cable 4A and supported by the hoist 1A; 3B, a cage of elevator B connected to one end of a cable 4B and supported by the hoist 1B; 5A, a balance weight of elevator A hung at the other end of the cable 4B; 5B, a balance weight of elevator B hung at the other end of the cable 4B; 6A a weighing apparatus for elevator A which produces a passenger-number signal 6Aa based on the live load in the cage 3A; 6B, a similar weighing apparatus for elevator B which produces a passenger-number signal 6Ba; 71 through 73, first through third floors, respectively; 81 through 83, call buttons provided at the first through third floors, respectively, beside the elevator doors at those floors in the connectional manner; 9A, a control circuit for elevator A for controlling the hoist 1A to cause the cage 3A to move up and down; 9B, a control circuit for elevator B for controlling the hoist 1B to cause the cage 3B to move up and down; and 10, an assignment computing circuit, having a function equivalent to that shown in FIG. 4 of U.S. Pat. No. 4,244,450, provided for computing the estimated time required for each elevator cage to arrive at the floor at which a call has been registered on the basis of the passenger-number signals 6A and 6B, information signals 9Aa and 9Ba of elevators A and B produced by the control circuits 9A and 9B, respectively, and including information as to cage positions, cage calls, running directions, etc., and information stored in assignment memories 11A and 11B, whereby the optimum one of the elevator cages (usually, the elevator cage which can respond to the hall call the earliest) is assigned to the call, with the assignment computing circuit 10 being provided commonly to the elevators A and B. The assignment memory 11A of elevator A serves to store calls assigned to the elevator A by the computing circuit 10 and produces a signal 11Aa indicative of such calls which is transmitted to the control circuit 9A. The assignment memory 11B of elevator B similarly produces a signal 11Ba.
Upon the actuation of one of the call buttons 83 in the elevator group control system arranged as described above, the call is inputted to the assignment computing circuit 10. In the assignment computing circuit 10, the estimated time required for each of the cages 3A and 3B to arrive at the floor 72 from which the call was received is computed. If it is determined that the estimated time for the cage 3A, for example, is the shorter, the call signal of the call button 82 is stored in the assignment memory 11A. The control circuit 9A causes the cage 3A to serve the floor 72 corresponding to the call signal stored in the assignment memory 11A.
In the case, for example, where a guest in a hotel wishes to use the elevator system, an indication of his need for an elevator can be transmitted to the elevator system only upon his or her arrival at the elevator area from his guest room, and hence it is necessary to wait for the arrival of an elevator cage from the point of time of call button depression at the elevator area. That is, since the transmission of the need for an elevator is delayed from the time the guest leaves his or her room until arrival at the elevator area, the overall waiting time may be lengthy, and a user particularly in a hurry may become impatient. To resolve this problem, although it may be considered to provide a call button in each guest room, there is a further problem in this case that a cage may arrive at the guest's floor so early that the doors of the case close and the cage leaves before the user arrives. In such a case, although it would be possible to cause the cage to wait for the user, the resulting prolonged wait of the cage at the guest's floor may lower the overall efficiency of the elevator system and result in a prolongation of the waiting time of other users.